In recent years, various attempts have been made to realize an automatic operation of a movable body such as a four-wheel vehicle. For realization of an automatic operation of a movable body, it is important to correctly detect objects such as vehicles, pedestrians, and obstacles present around the movable body and to avoid danger while running based on the detection results. Of these two factors, an object detection technology using various sensors and radars is known as a technology to precisely detect surrounding objects.
An automatic operation technology of a movable body is a technology by which the movable body is automatically moved from an origin to a destination only by entering the destination. When the range of movement is narrow, this technology can be realized in a path finding technology by creating a map of the range of movement in advance and predicting an influence of dynamic obstacles in advance. However, when the range of movement of a movable body is wide such as when the movable body is an automobile, the automatic operation technology cannot be realized in the path finding technology. The wide range here is a range in which a time t needed for avoiding a dynamic obstacle and a time τ needed for running an entire distance are vastly different and, for example, is a case in which τ is several hours while t is several seconds.
If the range of movement of a movable body is wide, there are mainly two reasons why the automatic operation technology is not attributable to the path finding technology. First, a first reason is as follows: Consider, for example, a situation when a time of about 10 t elapses after a movable body starts from an origin. In this case, an influence of dynamic obstacles spreads out over an entire road and a path on which no collision occurs cannot be defined. That is, if the range of movement of a movable body is wide, a path from an origin to a destination cannot be calculated in advance.
Next, a second reason is as follows: If the range of movement of a movable body is wide, as described above, the time τ needed for running an entire distance is much longer than t. Thus, it is impossible for a computer mounted on an automobile to complete required calculation within a practical time in which evasion of actual collision can be realized.
In the automatic operation technology of a movable body that moves in a wide range such as an automobile, as described above, in addition to the path finding technology in which an influence of at least other dynamic obstacles is not considered or an influence thereof is not practically needed for calculation, a path calculation technology by which calculation needed for avoiding collision with dynamic obstacles is completed within a practical time to calculate a path to avoid danger while running is needed.
As a technology to avoid danger while running of the path calculation technology described above, a technology is known by which, in a system consisting of a plurality of objects and subject vehicle, paths of each object including subject vehicle are generated by using information concerning the position and velocity of subject vehicle and information concerning the positions and velocities of the plurality of objects excluding subject vehicle to predict possibilities of any two objects constituting the system to collide (See, for example, Nonpatent Literature 1). According to this technology, paths taken by all objects constituting the system are predicted by means of operation sequences of the same framework using the concept of probability and are output. Then, based on obtained prediction results, a path for realizing the safest condition for the entire system including subject vehicle is determined and output.
Nonpatent Literature 1: A. Broadhurst, S. Baker, and T. Kanade, “Monte Carlo Road Safety Reasoning”, IEEE Intelligent Vehicle Symposium (IV2005), IEEE, (June, 2005)